Conversion of hydrocarbons with {37 Y{38 {0 faujasite-type catalysts

ABSTRACT

A FCC operation is described for separately converting with faujasite conversion catalyst, a gas oil feed material and a C3C4 rich hydrocarbon fraction. Conversion of the gas oil is accomplished in a normal riser reactor and conversion of the C3C4 rich hydrocarbons is accomplished with catalyst separated from the gas oil riser reactor in a restricted riser reactor confined within the catalyst collecting zone about the discharge end of the gas oil riser.

United States Patent 1191 Owen 1 1 CONVERSION OF HYDROCARBONS WITH Y"FAUJASITE-TYPE CATALYSTS [75] Inventor: Hartley Owen, Belle Meade, NJ.

[73] Assignee: Mobil Oil Corporation, New York.

[22] Filed: Nov. 19. 1973 [21] Appl. No.: 417,003

[52] U.S. Cl. 208/78; 208/74; 208/120; 208/l56; 208/164; 260/673;260/676 R [51} Int. Cl Cl0g 37/02;C10g l1/18',B01j 9/20 [58] Field ofSearch 208/78. 71. 62

[56] References Cited UNITED STATES PATENTS 2.908.630 10/1959 Friedman208/74 3.406.1 12 10/1968 Bowles 208/153 3.679.576 7/1972 McDonald208/74 1451 July 15,1975

12/1973 Youngblood et al. 208/74 1/1974 Reynolds et al. 208/74 PrimaryExaminer-Delbert E. Gantz Assistant Examiner-G. E. Schmitkons Attorney.Agent, or FirmCharles A. Huggett; Carl D. Farnsworth {57] ABSTRACT A FCCoperation is described for separately converting with faujasiteconversion catalyst. a gas oil feed material and a C C. rich hydrocarbonfraction. Conversion of the gas oil is accomplished in a normal riserreactor and conversion of the C -C rich hydrocarbons is accomplishedwith catalyst separated from the gas oil riser reactor in a restrictedriser reactor confined within the catalyst collecting zone about thedischarge end of the gas oil riser.

7 Claims, 1 Drawing Figure CONVERSION OF HYDROCARBONS WITH YFAUJASITE-TYPE CATALYSTS BACKGROUND OF THE INVENTION The field ofcatalytic cracking and particularly the operations related to dense anddilute fluid phase catalytic operations have been undergoing progressivedevelopment since early I940. As new experience was gained in operatingand design parameters, new catalyst compositions were developed whichprompted a further refinement in known operating technology. With thedevelopment of high activity crystalline zeolite catalyst, the industryfound a further need to improve upon its operating parameters to takeadvantage of the new catalysts activity, selectivity and operatingsensitivity. The present invention is thus concerned with an improvedmethod of cracking or catalytic operation which relates to catalystactivity and selectivity to processing parameters in a manner mutuallycontributing to improving the conversion of available refinery feedmaterials.

SUMMARY OF THE INVENTION The present invention is directed to theconversion of hydrocarbons in the presence of a relatively large porecrystalline material of the faujasite type of crystalline zeolite. In amore particular aspect, the present invention is concerned with morecompletely utilizing the activity and selectivity characteristics of Xand Y faujasite crystalline aluminosilicate conversion catalyst toupgrade gas oil feed materials and normally gaseous hydrocarbon productssuch as those obtained in a gas oil conversion operation. In yet anotheraspect the present invention is concerned with using a faujasitecracking catalyst separated from a gas oil hydrocarbon conversion zoneto upgrade particularly C and C, rich hydrocarbon gaseous materials tohigher boiling gasoline boiling material. The C -C rich gaseous materialmay be the product of a high temperature hydrocarbon cracking operationor the gaseous hydrocarbons may be recovered from other availablerefinery sources. More particularly, the present invention is concernedwith the cracking of high boiling hydrocarbons such as gas oil boilingrange hydrocarbons, residual oils and hydrogenated products thereofincluding a hydrogenated resid material with particularly a Y faujasitecracking catalyst under elevated temperature cracking conditionsselected from within the range of 900F. to about l,lF. at a hydrocarbonresidence time in a once through conversion zone restricted to withinthe range of l to about 12 seconds. Catalyst to oil ratios may beselected from within the range of 4 to about 20. Generally, it ispreferred to accomplish cracking of the gas oil in an upflowing riserconversion zone discharging into a separation zone such as an upperportion of an enlarged catalyst separation and collection vessel whereinproducts of gas oil cracking are separated from the catalyst used. Theriser suspension may be discharged directly into cyclonic separatingmeans attached to the end of the riser or into the enlarged vessel undervelocity reducing conditions causing catalyst particles to settle outand separate from vaporous hydrocarbons before encountering cyclonicseparation of entrained catalyst fines from hydrocarbon vapors. Theseparated catalyst is collected in a lower portion of the enlargedvessel for passage to a lower catalyst stripping zone wherein thecatalyst is stripped with countercurrent flowing stripping gas such assteam. The stripped products and products of cracking separated from thecatalyst upon discharge from the riser conversion zone are combined,removed from the enlarged vessel and passed to one or more down-streamseparation zones. In accordance with one aspect of this invention, arestricted or relatively short riser reactor discharging into catalystseparation means such as one or more cyclonic separators at the riseroutlet is provided within the upper portion of the enlarged vessel sothat the restricted riser extends upwardly from within the collected bedof catalyst to an upper portion of the vessel. In this arrangement thecatalyst separated from the gas oil conversion step at an elevatedtemperature is available for flow upwardly through the restricted riserconversion zone suspended in normally gaseous C C, hydrocarbon feedmaterial. In this invention, a C C rich hydrocarbon mixture is combinedwith faujasite con version catalyst separated from the gas oilconversion zone at an elevated cracking temperature to form a suspensionof catalyst to hydrocarbon feed ratio in the range of 5 to about 40 atan elevated suspension temperature in the range of about 700 to aboutI.U50F. The C -C rich hydrocarbon feed stream may be furnace heated toan elevated temperature in the range of 550F. to about 900F. beforeentering the restricted riser conversion zone. On the other hand, tovary the catalyst to hydrocarbon ratio within the restricted riserconversion zone, steam may be used along with the C;;C hydrocarbonstream. Also steam may be used to effect the lift characteristics of thesuspension to pass upwardly through the restricted conversion zone. Thesuspension formed as herein provided passes upwardly through therestricted riser conversion zone under conditions providing ahydrocarbon residence time within the range of l to about 10 secondsbefore discharge and separation of the suspension by cyclonic means.During this operation, the faujasite catalyst providing hydrogentransfer activity and cyclization selectivity converts the C -Chydrocarbons to aromatics; alkyl aromatics and low boiling gaseousmaterial.

Catalyst particles separated from the conversion zones herein identifiedare caused to flow downwardly to and through a stripping zonecountercurrent to rising stripping gas such as steam. The strippedcatalyst is then transferred to a catalyst regeneration zone not shownfor the removal of deposited carbonaceous material thereby heating thecatalyst to an elevated temperature.

It is contemplated providing separate stripping zones for strippingcatalyst separated from each riser conversion zone and adding heat toeach stripping operation. For example, either one or both strippingoperation may be provided with hot regenerated catalyst to raise thetemperature of the stripping zone. On the other hand. where a singlestripping zone is used, it may also be advisable to bring a stream ofhot regenerated catalyst into the stripping operation to maintain itsefficiency at a high value. It is also contemplated passing therelatively cold catalyst of the C -C hydrocarbon conversion step to alower portion of the gas oil separated catalyst stripping step andproviding multiple stripping gas inlets to the stripping zone.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a diagrammatic sketch inelevation of an arrangement of hydrocarbon conversion zones forcatalytically converting selected hydrocarbon feeds with a fluidconversion catalyst.

DISCUSSION OF SPECIFIC EMBODIMENTS Referring now to the FIGURE, there isshown a riser conversion zone 2 supplied with hot regenerated catalystby conduit 4 provided with a catalyst flow control valve 6. Steam isintroduced to a bottom portion of riser 2 by one or more steam inletconduits 8 external to and about a gas oil inlet conduit 10 whichprojects upwardly into the bottom portion of riser 2. A suspension ofcatalyst in dispersion steam is thus initially formed into which anupflowing gas oil feed is introduced providing a mix or catalyst-oilsuspension temperature of at least 950F. Steam may also be combined withthe oil charge. The suspension passes upwardly through riser 2 undervelocity conditions selected to provide a hydrocarbon residence timetherein preferably within the range of 2 to about 10 seconds. Theupflowing suspension in riser 2 is discharged from the end thereof as byslotted openings into an enlarged catalyst settling zone promoted byreduced vapor velocity. On the other hand, riser 2 may dischargedirectly into one or more cyclonic separating means or immediatelyadjacent the bell mouth opening thereto for separating fluid catalystparticles from hydrocarbon vapors. In the specific arrangement shown inthe FIGURE the suspension in riser 2 is discharged into an enlarged zoneor vessel I2 wherein separation of catalyst from hydrocarbon vapors isencouraged by a substantial reduction in the suspension velocity.Hydrocarbon vapors then pass through cyclonic separation means 14 forremoval of entrained fines before the hydrocarbon vapors pass into aplenum chamber 16 and removal from the vessel by conduit 18. Catalystseparated from hydrocarbon vapors by settling and in cyclonic means 14pass by diplegs 20 to a fluid bed of catalyst 22 therebelow maintainedin the lower portion of the vessel I2. The fluid bed of catalyst 22 isin open communication with a lower stripping zone 24 to which the fluidbed of catalyst moves downwardly to and through countercurrent to risingstripping gas introduced by conduit 26. Stripped catalyst is removedfrom a bottom portion of the stripping zone by conduit 28 for transferto a catalyst regeneration zone not shown. A portion of the catalystwithdrawn by conduit 28 may be recycled to the inlet of riser 2 when ahigher catalyst to oil ratio is desired. The fluid bed of catalyst 22separated from the riser conversion Zone 2 is normally (in the absenceof restricted riser 30) at an elevated temperature and from about F. toabout 75F. below the temperature employed at the inlet of the riserconversion zone 2. However. in accordance with this invention, a secondrestricted riser conversion zone is provided within vessel 12 and thepresence of such a restricted conversion zone will cause a furtherreduction in the catalyst bed temperature unless augmented as hereinprovided. Riser 30 extends from beneath the upper interface of bed 22into an upper portion of the vessel so that a suspension of catalyst andhydrocarbon vapors discharged from the upper end of riser 30 will besubstantially adjacent the inlet of a cyclonic separation means ordischarge directly into cyclonic separating means. Cata lyst separatedas by cyclonic means 14 is then returned to a lower portion of bed 22than the inlet to riser 30 by a dipleg 20 as shownv A catalystwithdrawal well about the inlet of riser 30 may be provided. A gaseoushydrocarbon feed such as a mixture of C -C hydrocarbons at a suitableelevated temperature is introduced by conduit 32 with or without steamintroduced by conduit 34 to the bottom of riser 30 with suspendedcatalyst particles from fluid bed 22 to form a mixture or suspension ata temperature within the range of 700F. to about l,O50F. The suspensionformed in a catalyst/oil ratio in the range of 5 to about 0 is passedupwardly through riser 30 under conditions to provide a hydrocarbonresidence time within the range of l to about 10 seconds. The upwardlyflowing suspension on riser 30 is discharged from the upper end thereofadjacent the inlet to cyclonic separation means or directly intocyclonic separating means on the riser outlet and positioned in theupper portion of the enlarged settling vessel 12. The dischargedsuspension is separated by catalyst settling in the specific arrangementof the FIGURE due to a drop in velocity and by the aid of cyclonicseparation means such as separators 14. The separated catalyst isreturned to the fluid bed of catalyst 22 by diplegs provided. Thedischarge end of risers 2 and 30 may be in a T connection and providedwith one or more cyclonic separation means on each end thereof so thatthe suspension passed upwardly through the risers will pass directlyinto the cyclonic separators. This method of handling the suspensiondischarged from the risers provides a more positive control on thecontact time between hydrocarbon vapors and catalyst particles.

The method and system of the FIGURE above described may be modified tosome considerable extent without departing from the concepts of thepresent invention. For example, riser 30 may be a separate riser, themajor portion of which is external to the vessel I2 in much the samemanner as riser 2 is external to the vessel. In this arrangement. theriser relied upon to upgrade C and lower boiling hydrocarbons may beprovided with hot freshly regenerated catalyst or catalyst separatedfrom the gas oil riser conversion step either before or after strippingthereof. In yet another embodiment, it is contemplated initiallycontacting freshly regenerated catalyst in the bottom portion of riser 2with a C;,-C hydrocarbon rich mixture to form a suspension andthereafter bringing the suspension in contact with gas oil feed materialin an upper portion of the riser at one or more spaced intervals beforedischarge thereof into catalyst-hydrocarbon vapor separating zones. Inone or more of the above embodiments, the C and lower boiling gaseousfeed components may contact active conversion catalyst of the faujasitetype at a temperature within the range of 800F. up to about l,lO()F. andthe gas oil feed may contact the catalyst preferably at temperatures inexcess of 900F. and as high as l,lUOF. In yet a further embodiment it iscontemplated employing a single riser system in which system the gas oilfeed initially contacts the hot freshly regenerated catalyst and astream of C and lower boiling gaseous hydrocarbons such as a C -C richstream is then brought in contact with the gas oil catalyst suspensionin a down-stream or upper portion of the riser conversion zone. In yetanother embodi ment it is contemplated providing an annular conversionzone about an upper extension of the stripping zone arranged so thatstripped hydrocarbons will bypass the catalyst in the annular conversionzone but all of the catalysts discharged from the riser conversion zonewill pass into the annular conversion zone before entering thestripping. zone. In this arrangement the feed to either theriser'orannular conversion zone may be either gas oil or a C -C richhydrocarbon stream.

Discussion OF SPEClFlC EXAMPLE Havihgv thus, generally described themethod and that no undue restrictions are to be imposed by reason 7 njthereof exceptla s defined by the following claims.

A series of conversion runs with an isobutylene rich 1 claim; a feedwere F l seleeteei temperflmre and hydro l. A method forupgradinghydrocarbons with a faucarborf res'dence condmons f the jasitecrystalline zeolite conversion catalyst which comoperations contemplatedby the present invention and prises val'latlons thereon- A eatalysl e pi REY passing a suspension of faujasite zeolite conversion was contactedunder the conditions identified In the Catalyst dispersed i a high ilihydrocarbon table below which produced the results identified. lt f tiat a temperature within the range f was observed upon examination of theproduct that a 950]? to about 1,l0()F. upwardly through a firstConsiderable amount of y e transfer Occurred riser conversion zone at ahydrocarbon residence along with the production of a significant amountof 15 time within h range f 2 to 10 seconds liquid P e The liquidProduet was ielemified as discharging the suspension from said firstconversion eonslstmg of toluene Xylenes. tl'lmethylben' zone into aseparation zone above a fluid bed of Zenes and naphthalenes- Runs weremade 313 l catalyst and passing separated catalyst into said ture of1,050F. and 850F. using a wide spread in hyfl id b d drocarbon residencetime. The operating conditions i i t l t rticles in an upper portion ofsaid selected thus support the variations in operating arfluid bed ofcatalyst with a hydrocarbon feed rich rangements contemplated by thisinvention without inin C and lower boiling hydrocarbons to form asecterfering with prior art operating conditions such as ond suspensionat a temperature in the range of those relied upon for converting a gasoil charge under 700 to 1.050F., elevated temperature crackingconditions. passing the second suspension comprising C hydro- TABLE UnitHopper (dense bed) Riser (dilute phase. steady state) Run No. 180C- 193194 195 196 197 Temp. F 1050I 1050 1050 850 850 1 gas, sec. 46 22 7 8 l7Cat/gas (wt/wt) 29 41 40 80 Conversion (NLB):

Unconv. butylene 5.4 8.7 17.4 27.4 9.1

Propylene 3.3 4.1 11.9 4.3 5.5

Isobutane 19.9 23.7 34.1 42.0 47.4

C5+ gaso. 3.3 4.3 19.8 13.8 17.3

Other Cr gases 39.1 32.4 8.0 2.5 6.5

16.8 l2 5 20.6 Coke 29.0 26.8 8.3 10.0 14.1

No liquid trap used It will be observed from these data, that at theshorter residence time used for the riser conversion runs, cracking ofisobutylene to lower molecular weight gases and to coke is much reduced.However, at total conversion levels of 82.6, 67.8 and 90.9% of theisobutylene, losses to undesirable products are 12.21% and the ratios ofisobutane to butylene plus propylene range from 1.15 to 3.25.

Thus run 195 effected at a high temperature and short residence timesupports the concept of the present invention where the hot freshlyregenerated catalysts contact the C -C rich feed initially in either aseparate riser reactor or in an initial portion of a single riserreactor followed by gas oil cracking. On the other hand, run 196supports that portion of the concept of this invention wherein apreviously used catalyst is contacted in a separate riser reactor or ina down-stream portion of a single gas oil riser reactor with the C -Crich gaseous hydrocarbon feed material. Thus in any of thesearrangements at Y faujasite conversion catalyst has activity andselectivity for hydrogen transfer reaction and olefin cyclizationreaction leading to the production of significant quantities ofisobutane and aromatics.

carbons upwardly through a second riser conversion zone extending froman upper portion of said fluid bed of catalyst into the upper portion ofa catalyst-hydrocarbon vapor separation zone, said second suspensionmaintained at a temperature, space velocity and catalyst/hydrocarbonratio selected to convert the C and lighter hydrocarbons to formaromatics,

separating hydrocarbon conversion products and catalyst upon dischargefrom said second conversion zone,

recovering hydrocarbon products of said conversion zones, and passingcatalyst separated from each conversion zone through a stripping zonebefore effecting regeneration thereof.

2. The process of claim 1 wherein a high boiling hydrocarbon is added atintervals to the suspension pass ing through the first conversion zone.

3. The process of claim 1 wherein high boiling hydrocarbon and gasiformdispersant are mixed with hot regenerated catalyst in an annular mixingzone to form a suspension thereof which is thereafter passed upwardlythrough said first riser conversion zone under hydrocarbon conversionconditions.

of the low boiling hydrocarbons in the second conversion zone isrestricted to within the range of 4 to [0 seconds.

7. The process of claim 1 wherein the catalyst to hydrocarbon ratio inthe second conversion zone is controlled in response to relatively inertgasiform material combined with said low boiling hydrocarbon feed.

* I! i il

1. A METHOD FOR UPGRADING HYDROCARBONS WITH A FAUJASITE CRYSTALLINEZEOLITE CONVERSION CATALYST WHICH COMPRISES, PASSING A SUSPENSION OFFAUJASITE ZEOLITE CONVERSION CATALYST DISPERSED IN A HIGH BOILINGHYDROCARBON FRACTION AT A TEMPERATURE WITHIN THE RANGE OF 950*F. TOABOUT 1,100*F. UPWARDLY THROUGH A FIRST RISER CONVERSION ZONE AT AHYDROCARBON RESIDENCE TIME WITHIN THE RANGE OF 2 TO 10 SECONDS,DISCHARGING THE SUSPENSION FROM SAID FIRST CONVERSION ZONE INTO ASEPARATION ZONE ABOVE A FLUID BED OF CATALYST AND PASSING SEPARATEDCATALYST INTO SAID FLUID BED, MIXING CATALYST PARTICLES IN AN UPPERPORTION OF SAID FLUID BED OF CATALYST WITH A HYDROCARBON FEED RICH IN C4AND LOWER BOILING HYDROCARBONS TO FORM A SECOND SUSPENSION AT ATEMPERATURE IN THE RANGE OF 700* TO 1,050*F., PASSING THE SECONDSUSPENSION COMPRISING C4 HYDROCARBONS UPWARDLY THROUGH A SECOND RISERCONVERSION ZONE EXTENDING FROM AN UPPER PORTION OF SAID FLUID BED OFCATALYST INTO THE UPPER PORTION OF A CATALYST-HYDROCARBON VAPORSEPARATION ZONE, SAID SECOND SUSPENSION MAINTAINED AT A TEMPERATURE,SPACE VELOCITY AND CATALYST/HYDROCARBON RATIO SELECTED TO CONVERT THE C4AND LIGHTER HYDROCARBONS TO FORM AROMATICS, SEPARATING HYDROCARBONCONVERSION PRODUCTS AND CATALYST UPON DISCHARGE FROM SAID SECONDCONVERSION ZONE,
 2. The process of claim 1 wherein a high boilinghydrocarbon is added at intervals to the suspension passing through thefirst conversion zone.
 3. The process of claim 1 wherein high boilinghydrocarbon and gasiform dispersant are mixed with hot regeneratedcatalyst in an annular mixing zone to form a suspension thereof which isthereafter passed upwardly through said first riser conversion zoneunder hydrocarbon conversion conditions.
 4. The process of claim 1wherein said high boiling hydrocarbon fraction is a hydrogenatedmaterial of at least gas oil boiling range.
 5. The process of claim 1wherein said C4 and lower boiling hydrocarbons comprise a fraction richin C3 and C4 hydrocarbons which are converted to aromatics and isobutanein said second conversion zone.
 6. The process of claim 1 wherein theresidence time of the low boiling hydrocarbons in the second conversionzone is restricted to within the range of 4 to 10 seconds.
 7. Theprocess of claim 1 wherein the catalyst to hydrocarbon ratio in thesecond conversion zone is controlled in response to relatively inertgasiform material combined with said low boiling hydrocarbon feed.